Modular turbine blade with separate platform support system

ABSTRACT

A modular turbine blade assembly ( 10 ) usable in a gas turbine engine ( 12 ) and formed from an airfoil ( 28 ) and an independent, modular platform ( 16 ) supported by one or more clevis arm supports ( 14 ) extending radially inward from the modular platform ( 16 ) to a disk is disclosed. The clevis arm support may support the modular platform while a separate dovetail attachment supports the generally hollow airfoil. The clevis arm support ( 14 ) may be formed from at least two arms ( 20, 22 ) designed to reduce stress from a pin receiving orifice ( 24 ) at a distal end ( 26 ) of the two arms ( 20, 22 ) to the platform ( 16 ). The independent arms ( 20, 22 ) minimize stress concentrations caused by centrifugal loading in the support. The arms ( 20, 22 ) may be modified independently of each other, such as thickness and support angle. The clevis arm support ( 14 ) enables use of a modular platform system for the modular turbine blade ( 10 ).

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Development of this invention was supported in part by the United States Department of Energy, Advanced Turbine Development Program, Contract No. DE-FC26-05NT42644. Accordingly, the United States Government may have certain rights in this invention.

FIELD OF THE INVENTION

This invention is directed generally to turbine airfoils, and more particularly to support systems in turbine airfoils in gas turbine engines.

BACKGROUND

Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,240 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.

Typically, turbine blades are formed from a root portion having a platform at one end and an elongated portion forming a blade that extends outwardly from the platform coupled to the root portion. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades typically contain an intricate maze of cooling channels forming a cooling system. Turbine airfoils are often supported via a root having multiple dovetail projections extending therefrom for attachment to a rotor. Alternative configurations of a support and connection system have been employed.

SUMMARY OF THE INVENTION

A modular turbine blade assembly usable in a gas turbine engine and formed from an airfoil and an independent, modular platform supported by one or more clevis arm supports extending radially inward from the modular platform to a disk is disclosed. The clevis arm support may support the modular platform while a separate dovetail attachment supports the generally hollow airfoil. The clevis arm support may be formed from one or more arms, such as, but not limited to, two arms, a first and second arm, that may be independently modified to reduce stress at an attachment device at a distal end of the two arms. In at least one embodiment, the attachment device may be a pin receiving orifice. The independent arms may be contoured for assembly between blades and designed to minimize stresses along clevis arm features. At attachment locations, one or more pin receiving orifices may be included at distal ends of the two arms.

The modular turbine blade for a gas turbine engine may be formed from a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a tip at a first end of the airfoil. The clevis arm support may support the modular platform while a separate dovetail attachment supports the generally hollow airfoil. The modular turbine blade may also include one or more modular platforms attached to a disc via clevis arm supports extending radially inward from the modular platform. The clevis arm support may be formed from a first arm and a second arm extending from the modular platform into contact with each other radially inward of the modular platform. A cross member may extend between the first and second arms forming an attachment device, such as, but not limited to, a pin receiving orifice radially inward of the cross member and between the first and second arms and forming a void between the cross member, the first arm, the second arm and the modular platform. In at least one embodiment, inner surfaces of the first arm, the second arm and the cross member may be planar inner surfaces.

The first and second arms may reduce stress at the pin receiving orifice at a distal end of the two arms. The clevis arm support may reduce stress in a number of ways. In particular, the first and second arms may be nonorthogonal and nonparallel to each other. The first arm may be positioned at a different angle relative to a longitudinal axis of the at least one clevis arm support than the second arm. One or more intersections of two or more sides forming the cross member, the first arm, and the second arm may be rounded. In another embodiment, each of the intersections of two or more sides forming the cross member, the first arm, and the second arm may be rounded. A thickness of the first arm may differ from a thickness of the second arm. The first arm may have a cross-sectional area with a width that is greater than a length, and the second arm may have a cross-sectional area with a width that is greater than a length. The first ends of the first and second arms closest to the generally elongated hollow airfoil may be further apart than second ends of the first and second arms at the cross member. A distal end of the cross member may be curved from a first side aligned with the first arm to a second side aligned with the second arm.

During assembly, the center link may be pinned at the platform and may be rotated around and between the airfoil into the disk, which helps facilitate the installation and alignment with the pin, pin receiving orifices and disk holes. During operation, the first and second clevis arms and pin inherently provide the ability to rotate along the pin axis through the pin receiving orifices to load the modular platform against the pressure side of the generally elongated hollow airfoil for sealing and vibratory dampening. For servicing or assembly, or both, the modular turbine blade assembly provides a configuration that makes the option of removing or replacing the platform, or both, while the blade remains attached in place in turbine engine possible. This feature is very beneficial in that the modular turbine blade assembly provides a lower cost replacement in contrast to repairing and replacing a full blade during service intervals.

An advantage of the modular platform is the ability to improve the castability of the airfoil by minimizing overhang features, which is primarily for single crystal airfoils. The platform can utilize a less challenging casting method such as directional/non directional solidification or single crystal if warranted.

Another advantage of the modular turbine blade assembly is that the pin and clevis hole arrangement provides the ability to be sized to achieve sufficient pin and clevis arm bearing area while minimizing stress within the hole. The features of the modular turbine blade assembly can be easily controlled during the manufacturing process to create close tolerances between the pin and holes in the clevis arms.

Yet another advantage of this the clevis arm support is that the clevis arm support may be formed from at least two arms, a first and second arm, that may be independently modified to reduce stress at a pin receiving orifice at a distal end of the two arms.

Another advantage of the clevis arm support is that the independent arms minimize stress concentrations caused by centrifugal loading through the support.

Still another advantage of the clevis arm support is that the support enables mass reduction to be achieved through use of the first and second arms of the clevis arm support relative to conventional attachments.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.

FIG. 1 is a perspective view of a modular turbine blade having features according to the instant invention.

FIG. 2 is a perspective view of the clevis arm support of the modular turbine blade.

FIG. 3 is a perspective view of the clevis arm support of the modular turbine blade.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-3, a modular turbine blade assembly 10 usable in a gas turbine engine 12 and formed from an airfoil 28 and an independent, modular platform 16 supported by one or more clevis arm supports 14 extending radially inward from the modular platform 16 to a disk is disclosed. The clevis arm support 14 may support the modular platform 16 while a separate dovetail attachment supports the generally hollow airfoil 28. The clevis arm support 14 may be formed from one or more arms, such as, but not limited to, two arms, a first arm 20 and second arm 22, that may be independently modified to reduce stress at an attachment device 24 at a distal end 26 of the two arms 20, 22. The independent arms 20, 22 may be contoured for assembly between blades 28 and designed to minimize stresses along clevis arm 20, 22 features. The independent arms 20, 22 minimize stress concentrations caused by centrifugal loading through the support 14. The arms 20, 22 may be modified independently of each other, by modifying elements such as thickness and support angle. With the airfoil 28 being attached to a disc separately from the modular platform 16, the modular platform 16 may be removed and replaced without removing the airfoil 28.

In at least one embodiment, as shown in FIG. 1, the modular turbine blade 10 may be formed from a generally elongated hollow airfoil 28 formed from an outer wall 30, and having a leading edge 32, a trailing edge 34, a pressure side 36, a suction side 38 and a tip 40 at a first end 42 of the airfoil 28. The clevis arm support 14 may support the modular platform 16 while a separate dovetail attachment supports the generally hollow airfoil 28. A modular platform 16 may be positioned at a second end 46 opposite to the first end 42 and may be supported by one or more clevis arm supports 14, as shown in FIGS. 1-3, extending radially inward from the modular platform 16. In at least one embodiment, as shown in FIG. 2, each clevis arm support 14 may include a first arm 20 sized to support the attachment device 24, which, in at least one embodiment, may be a pin receiving orifice 24. The first arm 20 may be formed from any appropriate configuration such as, but not limited to, an “I” beam profile. The pin receiving orifice 24 may have any appropriate size and configuration, such as, but not limited to, tubular.

In at least one embodiment, as shown in FIG. 3, the modular turbine blade 10 may include two clevis arm supports 14 per modular platform 16. The clevis arm support 14 may be formed from a first arm 20 and a second arm 22 extending from the modular platform 16 into contact with each other radially inward of the modular platform 16. The clevis arm support 14 may be formed from any appropriate material capable of adequately supporting the modular platform 16 and withstanding the high temperatures, vibrations and other elements. A cross member 48 may extend between the first and second arms 20, 22 forming a pin receiving orifice 24 radially inward of the cross member 48 and between the first and second arms 20, 22 forming a void 52 between the cross member 48, the first arm 20, the second arm 22 and the modular platform 16. The inner surfaces 58 of the first arm 20, the second arm 22 and the cross member 48 may be planar inner surfaces 58. In at least one embodiment, the first ends 76 of the first and second arms 20, 22 closest to the generally elongated hollow airfoil 28 may be further apart than second ends 78 of the first and second arms 20, 22 at the cross member 48. A distal end 80 of the cross member 48 may be curved from a first side 80 aligned with the first arm 20 to a second side 82 aligned with the second arm 22.

The first and second arm 20, 22, may reduce stress at the pin receiving orifice 24 at a distal end 26 of the two arms 20, 22. The clevis arm support 14 may reduce stress in a number of ways. In at least one embodiment, one or more intersections 54 of two or more sides 56 forming the cross member 48, the first arm 20, and the second arm 22 is rounded. In another embodiment, each of the intersections 54 of two or more sides 56 forming the cross member 48, the first arm 20, and the second arm 22 is rounded.

The first and second arm 20, 22, may also reduce stress at the pin receiving orifice 24 at a distal end 26 of the two arms 20, 22 in other ways. In particular, a thickness 60 of the first arm 20 may differ from a thickness 62 of the second arm 22. The length of the first and second arms 20 and 22 may be varied as well to reduce stress and to enable proper positioning of the pin receiving orifice 24. The first arm 20 may have a cross-sectional area with a width 64 that is greater than a length 66, and the second arm 22 may have a cross-sectional area with a width 68 that is greater than a length 70. The first and second arms 20, 22 may be nonorthogonal and nonparallel to each other. In particular, the first arm 20 may be positioned at a different angle 72 relative to a longitudinal axis 74 of the clevis arm support 14 than an angle 84 of the second arm 22 relative to the longitudinal axis 74.

The modular platform 16 may also include a center link 90 extending radially inward. The center link 90 may include one or more pin receiving orifices 24, one of which may be positioned near a distal end 26. The center link 90 may be positioned between the first and second arms 20, 22. The center link 90 may be coupled to the modular platform 16 via a pivot connection. The center link 90 may be attached to the modular platform 16 via a pivot connection formed from a pin 92 extending through a hole in the center link 90 and attached to arms 94, 96 via holes 98, 100 therein. The pin 92 enables the center link 90 to pivot around the blade 28 during installation and removal and enable minor platform circumferential differences. The center link 90 may be used for assembly and support of the center of the modular platform 16 from centrifugal loading. The center link 90 may assist in minimizing platform deflections between the first and second clevis arms 20, 22 to enable the center link 90 to fit around the airfoil contour because the center of the modular platform 16 is near the blade midchord, which limits clevis access.

During assembly, the center link 90 may be pinned at the platform and may be rotated around and between the airfoil 28 into the disk, which helps facilitate the installation and alignment with the pin, pin receiving orifices 24 and disk holes. During operation, the first and second clevis arms 20, 22 and pin inherently provide the ability to rotate along the pin axis through the pin receiving orifices 24 to load the modular platform 16 against the pressure side 36 of the generally elongated hollow airfoil 28 for sealing and vibratory dampening. For servicing or assembly, or both, the modular turbine blade assembly 10 provides a configuration that makes the option of removing or replacing the platform, or both, while the blade remains attached in place in turbine engine possible. This feature is very beneficial in that the modular turbine blade assembly 10 provides a lower cost replacement in contrast to repairing and replacing a full blade during service intervals.

The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention. 

1. A modular turbine blade (10) of a gas turbine engine comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a tip at a first end of the airfoil; and a modular platform attached to a disc via at least one clevis arm support extending radially inward from the modular platform, wherein the at least one clevis arm support is formed from a first arm and a second arm extending from the modular platform into contact with each other radially inward of the modular platform, wherein a cross member extends between the first and second arms forming an attachment device radially inward of the cross member and between the first and second arms and forming a void between the cross member, the first arm, the second arm and the modular platform.
 2. The modular turbine blade of claim 1, wherein the attachment device is a pin receiving orifice.
 3. The modular turbine blade of claim 1, wherein at least one intersection of two or more sides forming the cross member, the first arm, and the second arm is rounded.
 4. The modular turbine blade of claim 1, wherein inner surfaces of the first arm, the second arm and the cross member are planar inner surfaces.
 5. The modular turbine blade of claim 1, wherein a thickness of the first arm differs from a thickness of the second arm.
 6. The modular turbine blade of claim 1, wherein the first arm has a cross-sectional area with a width that is greater than a length, and the second arm has a cross-sectional area with a width that is greater than a length.
 7. The modular turbine blade of claim 1, wherein the first and second arms are nonorthogonal and nonparallel to each other.
 8. The modular turbine blade of claim 7, wherein the first arm is positioned at a different angle relative to a longitudinal axis of the at least one clevis arm support than the second arm.
 9. The modular turbine blade of claim 1, wherein first ends of the first and second arms closest to the generally elongated hollow airfoil are further apart than second ends of the first and second arms at the cross member.
 10. The modular turbine blade of claim 1, wherein a distal end of the cross member is curved from a first side aligned with the first arm to a second side aligned with the second arm.
 11. The modular turbine blade of claim 1, further wherein a center link extending radially inward from the modular platform and positioned between the first and second arms.
 12. The modular turbine blade of claim 11, wherein the center link is coupled to the modular platform via a pivot connection. 